The present invention relates to a polyglycidyl compound useful as an epoxy resin and a process for the preparation thereof, and more particularly to an epoxy resin obtained from gallic acid or tannic acid by introducing glycidyl groups to hydroxyl and carboxyl group of gallic or tannic acid.
Hitherto, various polyglycidyl compounds have been prepared by reacting polyhydric phenols, carboxylic acids or amines with epihalohydrins to introduce glycidyl groups, and have been employed as epoxy resins. It is expected that polyglycidyl compounds obtained by using aromatic polyhydroxycarboxylic acids as starting materials have characteristics useful as epoxy resins. Gallic acid and tannic acid which is the condensate of gallic acid. are known as aromatic polyhydroxycarboxylic acids which are abundantly present in nature and are easily obtainable.
On the other hand, introduction of glycidyl groups to compounds having both of carboxyl group and phenolic hydroxyl group by the reaction thereof with epihalohydrins has not been easy in general, since the produced glycidyl ester moiety is subject to hydrolysis owing to an aqueous alkali solution.
An object of the present invention is to provide a novel epoxy resin.
A further object of the invention is to provide a novel epoxy resin derived from gallic acid or tannic acid present abundantly in nature and easily obtainable.
Another object of the invention is to provide a process for preparing an epoxy resin with ease in high yields from gallic acid or tannic acid.
These and other objects of the present invention will become apparent from the description hereinafter.